The ability to sense wetness in a disposable absorbent article (e.g., diaper, training pants, incontinence pad, etc.) has been a desirable feature for a variety of modern hygiene products. Because these articles are so absorbent, for example, wearers may not realize they have urinated, particularly if they are inexperienced toddlers who may not recognize the meaning of body sensations associated with urination. Thus, the wearer may not recognize their urination control failure or be aware the article should be changed. Furthermore, parents or caregivers may not recognize that the absorbent article requires changing. Various attempts have been made to solve the problems noted above. U.S. Patent Publication No. 2010/0030173 to Song, et al., for example, describes a wetness sensor formed from a leuco dye and color developer (e.g., zinc salicylate) that exhibits a visual signal in a dry state. Upon contact with a bodily fluid, such as urine, the signal begins to fade or completely disappear. Unfortunately, such sensors often require the use of a surfactant to achieve sufficient wetting on the surface of the absorbent article, which increases the costs and complexity of the sensor. Furthermore, such sensors are also relatively insensitive to small amounts of fluids, and they can sometimes take a long time to undergo the desired color change.
As such, a need currently exists for an improved wetness sensor that can undergo a rapid color change in the present of bodily fluids.